= Deep inelastic scattering
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Scattering that resolves the constituents of a <hadron> at large spacelike <momentum transfer>, with an inclusive sum over final <hadron> states.
In <electron> scattering from a <proton>, write the reaction as $e^-p\to e^-X$: the outgoing <electron> is measured, while $X$ denotes all allowed final <hadron> states. Large <momentum transfer> supplies a short-distance probe; a large final <invariant mass> separates the deep continuum from <elastic scattering> and individual <particle resonances>. The useful surprise is that an extended <proton> can have a response characteristic of much smaller constituents. <Deep inelastic scattering> turns measurements outside the <proton> into constraints on its internal <parton distribution functions>.
The <SLAC-MIT deep inelastic electron scattering experiment> connects this definition to an actual measurement. Its evidence came from distributions of outgoing <electron> <energies> and <scattering angles>, rather than a photograph of a <quark>. <Bjorken scaling> concerns <deep-inelastic structure functions> after known scattering factors have been accounted for; it does not say that the raw <differential scattering cross-section> is constant.
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